Yarn twister



United States Patent 3,530,658 YARN TWISTER Dennis E. Johnson, Cambridge, Mass., assignor to Arthur D. Little Inc., Cambridge, Mass., a corporation of Massachusetts Filed Nov. 17, 1969, Ser. No. 877,375 Int. Cl. D01h 1/10 [1.5. CI. 5758.67 9 Claims ABSTRACT OF THE DISCLOSURE A three-for-one yarn twister particularly suitable for twisting fibers of synthetic materials directly following spinning through spinnerettes, the twister having a driven, hollow spindle with a bobbin support disposed on the spindle for coaxial rotation independently of the latter. An axially moveable traveler is also mounted on the spindle for rotation independently of the latter, the spindle and traveler being counter-rotatable.

This invention relates to textile twisting and more particularly to a system for providing twisted yarn of synthetic fibers.

It is known that in the conversion of fibers, either discrete (i.e., staple form) or continuous length, to yarn, it is desirable for a number of known reasons to import a twist, either false or real, to the yarn. There are a number of systems which apply either real or false twist to yarns, but some are not applicable to spinning of yarns directly received from a continuous fiber extrusion process.

The term spinning as used herein in connection with the formation of synthetic fiber, is generally understood in the industry to refer to the chemical transformation of a liquid or melt into one or more continuous fila- 'rnents. This usage should be distinguished from the process, also known as spinning, in which staple is mechanically transformed into yarn, typically in connection with cotton, worsted and other natural fibers.

To provide twist to yarns, the prior art has used the so-called 2-for-1 twister in which a wound bobbin is emplaced on a driven spindle. The bobbin is unwound by passing the yarn from the bobbin through the top of a hollow center of the spindle and out of the bottom of the spindle through a tube extending at right angles to the spindle. The yarn coming out of the latter is then fed through a pigtail guide located above the spindle. This system in operation, whirls a balloon of yarn about the spindle, the balloon wholly enclosing the bobbin. Obviously, because this twister serves to impart twist only as the yarn package unwinds, it is not suitable for use with yarn coming directly from an extruder.

The prior art more commonly employs the ring-andtraveler systems in which yarn is fed into, rather than out of, a pigtail guide and hence to a traveler mounted on a movable ring. The ring is disposed for rotation coaxially about a driven spindle, and the yarn is fed from the traveler to a bobbin on the spindle. The ring typically can be translated along the axis of the spindle, hence as the spindle rotates, a tapered package can be laid onto the bobbin. By governing the speed of rotation of the spindle relative to the rate at which yarn is permitted to be fed through the pigtail guide, twist can be imparted to the yarn, but the maximum is one twist per full turn about the spindle.

The present invention therefore has as a principal object provision of a method and system for imparting true twist to a yarn. Other objects are to provide such a system wherein a high degree of twist is imparted; to provide such a system which is particularly useful in ice a continuous yarn spinning such as is necessary with a continuous fiber extrusion process; to provide such a system capable of operating at very high speeds so that large lengths of yarn per unit time can be processed; and to provide such a system which is simple, easy to operate and inexpensive to manufacture.

Other objects of the invention will in part be obvious and will in part appear hereinafter. The invention accordingly comprises the processes involving the several steps and the relation and order of one or more of such steps with respect to each of the others, and the products and compositions possessing the features, properties and relation of elements which are exemplified in the following detailed disclosure and the scope of the application all of which will be indicated in the claims. For a fuller understanding of the nature and objects of the present invention, reference should be had to the following detailed description taken in connection with the accompanying drawing wherein there is shown schematically in cross section a system embodying the principles of the present invention.

The present invention briefly comprises a rotatable spindle about which yarn is wound, the spindle being driven in rotation about a vertical axis. Also disposed for rotation about the same axis are a bobbin support and a traveler, all rotatable independently of the spindle and one another.

The term twist implies that a length of a yarn has imparted thereto a force which forces the yarn fibers to lie along at least a full (i.e., 360) helix about the long axis of the yarn. A false twist is one where there is a spatially periodic reversal of the twist direction. Hence, tension applied to a length of yarn containing such a twist reversal will untwist the yarn. A true twisted yarn cannot be so untwisted for the twist is continuous in the same direction.

The prior art includes a number of well driven devices such as ring-and-traveler systems over which the present invention is an improvement. Such systems are particularly well suited to providing true twisted yarns. In these prior art, ring-and-traveler systems as in the present inventon, about 360 of real twist will be imparted to the yarn for each 360 of rotation of the traveler. Thus the rate of twist (Q) is equal to the rotational speed (N (revolutions per unit time) of the traveler or as the difference between the rotational speed (N of the spindle and rotational speed (N,,) of the traveler. These relations then give Where D is the spindle diameter or effective diameter of the bobbin at the point of lay. If new one defines twist in terms of twist per wrap (T), e.g., the twist per inch of yarn (t) multiplied by the spindle circumference, then Equation 2 can be written as (3) T=f1rD Twist per wrap can also be defined as the ratio of the rate of twist to the rate of wrap or and substituting Equations 1 and 2 into 4, one obtains Rearranging the preceding, one obtains the following relations:

Now if one graphs to and T against N /N it will be seen that T is asymptotic to T:l and N /N =+1. This means that T is largest where N /N approaches unity. When N /N is either much greater or much smaller than unity, T approaches one twist per wrap as its limit. When T approaches a maximum value, then w/N which is a measure of production rate, approaches zero. This seems to indicate that in the prior art ring-andtraveler system, for a given spindle speed a compromise must be made between the rate of production and the amount of twist imparted to the yarn.

Thus, high twist at high production rates required high spindle speeds. Typically, prior art devices were capable of generating 0.8 twist/inch using a spindle with a diameter of 2.5 inches rotating at 12,000 rpm. as a high rate of production. The present invention through a novel adaptation of the prior art, achieves a twist/inch for a production rate in yards/minute comparable to the prior art at considerably slower spindle velocity, or from a different point of view achieves a considerably greater production rate at the highest spindle velocities of the prior art with a comparable twist/inch.

To effect the foregoing, the present invention uses a principle which can be termed 3-for-1 and which is embodied in a device such as is shown in the drawing. The latter device includes central elongated, cylindrical spindle 20, preferably disposed vertically and supported adjacent its lower end by appropriate spindle bearings 22 and 24 so as to be rotatable about its long axis. Spindle includes a central bore 26 extending from opening 28 at the top end of the spindle to an intermediate point 29 preferably adjacent the bottom end of the spindle. Mounted on spindle 20 and extending perpendicularly to the axis of the latter is whorl tube 30. The latter can be a separate element as shown, or formed integrally with spindle 20, and includes a central bore 32 connected at one end to bore 26 at point 29 and having an opening 34 at the other end. Both openings 28 and 34 are preferably belled or flared outwardly and are surfaced with ceramic fittings (not shown). The junction between bores 32 and 26 is preferably smoothly rounded internally.

As means for driving spindle 20 in rotation within bearings 22 and 24 coaxially about bore 26, the embodiment of the invention includes motor 36 connected for driving endless belt 37. The latter is mounted about pulley 38 (which is driven by motor 36) and about circumferential belt-slot 39 cut into spindle 20 between spindle bearings 22 and 24.

Mounted for rotation about the circular periphery of spindle 20 adjacent whorl tube is rotor bearing 40, a similar rotor bearing 42 being also provided about spindle 20 at a position intermediate the upper end of the latter and bearing 40. Elongated hollow cylindrical rotor 44 is mounted coaxially about spindle 20 on bearings 40 and 42 for rotation independently of the spindle about the long axis of the latter.

As means for driving rotor 44 in rotation, the rotor is provided with a number of magnetic or magnetizable rotor pole pieces such as 45 and 46 extending in a common plane radially outward with respect to the axis of rotation of the latter. The device is also provided with a plurality of stator pole pieces such as 47 and 48 disposed in the same plane as the rotor poles and spaced outwardly from the latter. Stator pole pieces 47 and 48 are selectively magnetizable to drive the rotor pole pieces. Because the structure and technique of electromagnetic drive systems of this type is so well known, only the pole pieces of the system are schematically shown. Removably and coaxially mounted about rotor 44 is hollow cylindrical spool or bobbin 50 upon which yarn package 52 is to be wound. Means are provided, typically in the form of pin 54 fixedly connected to pole 46 and positioned to be engageable with a corresponding hole in an edge of bobbin 50. As thus far described, the system shown in the drawings is quite similar to the prior art 2 for 1 twister.

However, the present device includes traveler rotor 56 formed as a disk or a wheel having a plurality of radial arms or the like. Rotor 56 is mounted for rotation about bearing 58, the latter in turn being mounted on spindle 20 adjacent the upper end of the latter. Bearing 58 is both rotatable about and independently of spindle 20 and translatable along the latter. Depending downwardly adjacent the periphery of rotor 56 is traveler arm 60 having an opening 62 adjacent its distal end 63. Arm 60 is so dimensioned that translation of rotor 56 along spindle 20 can move opening 62 along a line parallel to the axis of spindle 20 and between respective positions radially opposite respective end portions of bobbin 50. Arm 60 is held by rotor 56 at a radial distance from the bobbin sufficient to allow a reasonably sized yarn package 52 to build up on the latter. To move rotor 56 both in rotation and translation, the rotor can also be driven electromagnetically. Thus schematically, rotor 56 includes magnetized rotor pole pieces 64 and 65 separated radially from one or more stator pole pieces 66 and 67. The latter are preferably mounted, on support means such as rail 68, for movement along a line parallel to the long axis of spindle 20. Movement of the stator pole pieces on supporting rails preferably is effected by known devices (not shown). Preferably, rotor 56 and its associated bearing 58 can be slipped off of spindle 20 to permit removal or insertion of bobbin 50.

Lastly, the system includes a yarn guide such as pigtail guide 70 supported on suitable means in a fixed position preferably above and colinear with the axis of the spindle.

In operation, typically a bundle of fibers forming a yarn, shown as dashed line 72, is threaded thru the pigtail guide 70, between rotor 56 and the stator pole pieces 66 and 67 to opening 34. The yarn then passes through bores 32 and 26, out of openings 28, back between rotor 56 and the stator pole pieces 66 and 67, through opening 62 and is attached to bobbin 50. Motor 36 drives spindle 20 in rotation whilst appropriate electromagnetic impulses applied by stator pole pieces 47 and 48 dri-ve rotor 44 in rotation, and those applied by stator pole pieces 66 and 67 drive rotor 56 in rotation.

For proper operation, spindle 20 and traveler rotor 56 should counter-rotate. Each rotation of the spindle per se through 360 imparts 2 twists onto yarn 72 being wound on the bobbin. Each rotation of traveler arm 60 per se through 360 imparts a single twist. Thus, if spindle 20 rotates clockwise (looking down from the top of the spindle), two Z twists are imparted to the yarn, the counterclockwise rotation of arm 60 then providing a third Z twist. Conversely, each counterclockwise rotation of the spindle and accompanying clockwise rotation of the traveler arm provides three S twists.

The bobbin may or may not be driven if one Wishes. The bobbin preferably is driven to rotate in the same direction as the traveller arm but at a somewhat different speed, either faster or slower.

The bobbin can also, if one wishes, rotate in the opposite direction to the traveller to achieve extremely high winding speeds which however necessarily reduces the total twist per unit length achieved.

It will be appreciated that the invention generally then is formed of three independent rotors, one of which provides two twists per revolution to the yarn, a second of which adds another twist per revolution and the third of which achieves winding of the trebly twisted yarn.

Since certain changes may be made in the above ap paratus without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted in an illustrative and not in a limiting sense. For example, it will be appreciated that operation of the device as shown will produce a double-balloon, an outer balloon extending from pigtail guide 70 to opening 34 of whirl tube 30, and an inner balloon extending from opening 28 in the spindle to opening 62 in the traveler arm. Both balloons then will pass through the interspace between stator pole pieces 66 and 67, and rotor 56. To prevent any undesirable and inadvertent entanglement between the two balloons, the periphery of rotor 56 can include a guide slot or opening for the inner balloon which only rotates as fast as the traveler arm anyway. Such an arrangement would of course insure that the two balloons do not engage one another, at least between rotor 56 and its associated stator pole pieces. Also, if one wishes, the various rotors can all be driven mechanically by suitable coaxial sleeves each coupled, as by appropriate gearing, to a respective motor.

What is claimed is:

1. A device for twisting and winding yarn on a hollow bobbin, and comprises, in combination a hollow elongated spindle mounted for rotation about its long axis and having a hollow whorl tube extending substantially normally to said axis, the interior of said spindle and tube forming a continuous passageway;

rotor means for supporting said bobbin around said spindle for rotation about said axis independently of said spindle; and

a traveler element mounted for rotation about said axis independently of both said spindle and said rotor means and including a yarn guide radially spaced from the outer surface of said bobbin between the ends of the latter.

2. A device as defined in claim 1 including means for independently driving in rotation said spindle, said rotor means and said traveler element.

3. A device as defined in claim 2 wherein said means for driving said rotor and said traveler element are electromagnetic.

4. A device as defined in claim 1 wherein said whorl tube is disposed toward one end of said spindle, said traveler element is disposed toward the other end of said spindle and said rotor means is positioned about said spindle between said whorl tube and said traveler element.

5. A device as defined in claim 4 wherein said traveler element is also mounted for movement axially with respect to said spindle between a pair of positions at which said yarn guide respectively lies adjacent corresponding ends of said bobbin.

6. A device as defined in claim 5 wherein said traveler element is removable from one end of said spindle so as to permit insertion or removal of said bobbin from said rotor means.

7. A method of imparting twist to yarn during winding of the latter about a spool and comprising the steps of threading said yarn through a hollow elongated spindle having a substantially perpendicular whorl tube, the interiors of which form a continuous passageway, said yarn extending from a first guide coaxially located above said spindle through said whorl tube to an opening at one end of said spindle;

threading said yarn from said one end of said spindle through a second yarn guide disposed in a traveler element independently rotatable about said spindle to a bobbin mounted for rotation independently about said spindle;

rotating said spindle in a first direction to form a first yarn balloon extending from said first guide to said whorl tube, so as to impart up to two full turns of twist to said yarn for each full revolution of said spindle;

rotating said traveler element in an opposite direction to form a second yarn balloon coaxial with said first balloon and extending between said opening and said second yarn guide and to impart up to a third full turn of twist to said yarn for each revolution of said element; and

rotating said bobbin so as to wind said yarn after said twists have been imparted thereto.

8. The method as defined in claim 7 wherein said bobbin is rotated at an angular speed diiferent from the angular speed of rotation of said element.

9. The method as defined in claim 8 wherein said bobbin is rotated in the same direction as said element.

References Cited UNITED STATES PATENTS 2,537,506 1/1951 Beria 57-5868 2,575,476 11/1951 Truitt 57-5858 3,377,790 4/1968 Brockel 5758.67 XR 3,368,336 2/1968 Franzen 5758.67 3,406,511 10/1968 Nimtz et al. 57-58.65

JOHN PETRAKES, Primary Examiner US. Cl. X.R. 5758.83 

